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SMTP (Cannot resolve)


andrewgroup
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Attached is a diagram showing a 3 NIC XP PBXnSIP... Before you jump on the DNS server is the problem hear me out.

 

we can configure any number of email clients (outlook express) to use the 192.168.1.6 IP address as the mail server and it will successfully bound mail of of the SBS 2003 Mail Server. (Yes the IP address of the PBX is in the allow relay settings that allows outlook express to work correctly.

 

Only the 192.168.1.250 has a gateway .1.... (Note .1 is a linux gateway with an SMTP mail server and Outlook Express can send via it too..

 

The 100.x network is a private network going to the Epygi T1 gateway only...

 

The Public IP ISP provider has no Mail Server to use as a test..

 

This setup had worked for some time, I've restored a original copy of the pbxnsip executable to no avail...

 

Thinking outside the BOX, does the PBXnSIP service somehow bind itself to a specific Interface and somehow that has happened that will not allow the DNS queries or the SMTP transactions to occur on the correct interface?

 

mail settings have been set to the local FQFN of the mail server with matching entries in the hosts files

DNS has been removed from all NICS and used the Mail Server IP's only

DNS only on the LAN IP.

 

Doing most of this testing remote, means we can't remove the gateway on the public IP...but could the LAN IP as a test. Just occurred and will do noew and post tommorrow. If fails, kind of thinking a rebuild.... or a LAN issue exists with a switch or router.

 

Cheers

PBX.pdf

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Thinking outside the BOX, does the PBXnSIP service somehow bind itself to a specific Interface and somehow that has happened that will not allow the DNS queries or the SMTP transactions to occur on the correct interface?

 

No, the PBX always binds the DNS socket to "anything" (0.0.0.0 in IPv4 and :: for IPv6). Was that the question?!

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No, the PBX always binds the DNS socket to "anything" (0.0.0.0 in IPv4 and :: for IPv6). Was that the question?!

 

for some unknown reason, the local windows applications like outlook express, telnet, mailtester, all seem to be able to successfully bounce email off of the smtp mail server at 192.168.1.5 but the PBX executable does not and creates the "CANNOT RESOLVE" entry in the Log file. The configuration jhas been set to the IP address, a DNS entry, a DNS entry with a matching entry in the local HOSTS file.

 

We've replaced the original executable from the ZIP file, but no Love.

 

This may prove to be an elusive LAN issue related to routers etc, Could a license expire and cause a problem like this?

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for some unknown reason, the local windows applications like outlook express, telnet, mailtester, all seem to be able to successfully bounce email off of the smtp mail server at 192.168.1.5 but the PBX executable does not and creates the "CANNOT RESOLVE" entry in the Log file. The configuration jhas been set to the IP address, a DNS entry, a DNS entry with a matching entry in the local HOSTS file.

 

We've replaced the original executable from the ZIP file, but no Love.

 

This may prove to be an elusive LAN issue related to routers etc, Could a license expire and cause a problem like this?

 

It is not a license problem. DNS also works without license.

 

Maybe the Microsoft applications find the email server because of some Active Directory or other Microsoft-specific mechanisms. There are a lot of packets flying around when you look at Wireshark...

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It is not a license problem. DNS also works without license.

 

Maybe the Microsoft applications find the email server because of some Active Directory or other Microsoft-specific mechanisms. There are a lot of packets flying around when you look at Wireshark...

 

If this was a member of a local domain, and yes a ton of packets are flying about when using Wireshark when trying to capture the ARP/SMTP queries.

I assume the ARP table would be shared across all applications. An onsite visit is in order to find the cause../solution. Will post the fix here if it's not a LAN/MAC table problem in a switch or router. (wishful thinking)

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  • 3 weeks later...

We did an in place upgrade from 2.1.5.2357 (Win32) to pbxctrl-3.4.0.3201 and the SMTP services immediately began working. A roll Back returned SMTP to non-functioning.

 

We began getting a could_not_read_file error so we put it in reverse.

 

What if any file formats may have changed? Cheers

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RESOLVED....

 

Summary...

 

Manually upgrading the 2.x controller to 3.4 controller the system immediately began sending old messages.... So I have safely assumed the problem is the 2.x controller.

 

Restoring the 2.x controller and changing some logging options, I was able to get an error log showing an SMTP error and an associated IP address that was not the IP address of the mail server as configured in the appropriate spot. Several things have contributed to the fix, but the exact cause/affect is not known, Deleting a large number of messaged from the spool folder.. 20K.... The system failed and began saving messages at 1, so the blame can't be the number of messages in the spool folder, but V3.4 might handle that larger number better and it began sending them...That was the clue.

Disabled a Public Facing NIC... so the route table would have 0.0.0.0 on the lan with the Mail server. Not sure it was wrong though..

 

Restored the 2.x controller and the email system began working as expected.

 

(I'm guessing that the files in the spooler might actually contain some information about the mail server on how to send the message. (This might have been the indication I captured with a bad mail server IP address. This may have once changed, causing the backlog... V3 may do it differently.. Just a SWAG.

 

Cheers

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